From the document DE 103 05 241 A1, a six- or seven-gear dual clutch transmission is known. The dual clutch transmission comprises two clutches, each of which is connected on their input sides to the input shaft and on their output sides to one of both transmission input shafts. Both of the transmission input shafts are arranged coaxially with respect to one another. Two countershafts are further arranged axially parallel to both transmission input shafts, and have idler gears that mesh with fixed gears of the transmission input shafts. Furthermore, the coupling devices are held rotationally fixed but axially shiftable to the countershafts in order to allow shifting of the particular gear wheels. The respectively selected gear ratio is transmitted to a differential gear by power take-off gears. In order to implement the desired transmission steps in the known dual clutch transmissions, a plurality of gear planes are required, such that a considerable amount of space is necessary for their installation.
A multistep spur gear transmission is further known from the published document DE 38 22 330 A1. The multistep spur gear transmission comprises a power-shifted dual clutch transmission, one part of which is connected to an input shaft and its other part is connected to a hollow input shaft that is rotatably mounted on the input shaft. For certain gear ratios, the input shaft can be coupled to the hollow input shaft via a shift element.
A power shift transmission with two clutches, each associated with a part transmission, is known from the published document DE 10 2004 001 961 A1. The transmission input shafts of both part transmissions are arranged coaxially with respect to one another and mesh with idler gears of the associated countershafts via fixed gears. The respective idler gears of the countershafts can be non-rotatably connected to the corresponding countershafts via associated shift elements. Among other things, a seven-speed transmission is known from the published document, and in which a further shift element is provided for coupling both transmission input shafts to implement another transmission step. In this embodiment, the seven-speed transmission requires at least six gear planes in both part transmissions to allow the transmission steps to be implemented. This results in an undesired extension of the overall length in the axial direction so that the possibilities of installing it in a vehicle are considerably limited.